The background description provided here is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
An internal combustion engine combusts air and fuel within cylinders to drive pistons and produce drive torque. Subsequent to startup and when a temperature of the engine is greater than a first threshold, coolant is circulated through one or more cylinder heads of the engine and an engine block and may also be circulated through an integrated exhaust manifold. The coolant is circulated to prevent the temperature of the engine from exceeding a second threshold. The temperature and/or flow rate of the coolant may be adjusted to control cooling of the engine, engine block, and integrated exhaust manifold and/or maintain predetermined temperatures of the engine, engine block and integrated exhaust manifold. The predetermined temperatures may be (i) greater than the first threshold, (ii) less than the second threshold, and (iii) maintained to maximize fuel efficiency of the engine.